Gas lift valve mandrel for well pipe strings



Feb. 24, 1970 H. u. GARRETT GAS LIFT VALVE MANDREL FOR WELL PIPE STRINGS 2 Sheets-Sheet 1 Filed April 18, 1968 A TTOR/VEYS I Feb. 24, 1970 RM. GARRETT 3,496,953

GAS LIFT VALVE MANDREL FOR WELL PIPE STRINGS AE/V a. 6 r

INVE $2.3 S v BY United States Patent Ofice 3,496,953 Patented Feb. 24, 1970 3,496,953 GAS LIFT VALVE MANDREL FOR WELL PIPE STRINGS Henry U. Garrett, Udell Garrett Inc., P.0. Box 21152, Houston, Tex. 77026 Filed Apr. 18, 1968, Ser. No. 722,477 Int. Cl. F0411? 1/08; F161: 13/06; E21b 29/02 U.S. Cl. 137-71 7 Claims ABSTRACT OF THE DISCLOSURE A gas lift mandrel particularly adapted to be preinstalled in well production pipe strings and including a tubular body having longitudinally extending passage means confined between the inner and outer wall surfaces of the body for establishing fluid communication between the interior and exterior of the body, the inner end of the passage means being initially closed off by the inner wall surface of the body, a gas lift valve mounted within the passage means in flow-controlling relation thereto, and the interior of the body having means, operable when required, to position a wall-perforating device in registry with the inner end of the passage to open the latter to communication with the interior of the body.

When oil wells have been completed it is found in many cases that after production has continued for some time, the natural pressure will become depleted and artificial means must be employed to continue production of the oil. One of the common systems for artificial lift is generally referred to as gas lift in which gas under pressure is injected itno the production pipe string through gas lift valves under controlled conditions to assist in lifting the well fluids to the surface.

Ordinarily, the gas lift valves will not be installed until after the natural lifting forces have been depleted. This involves removing the production tubing and installing a number of gas lift valves at spaced intervals along the tubing and then running the latter back into the well to re-establish the production pipe string. This type of installation necessarily involves considerable difficulty and hazard to the well, and is particularly diflicult and hazardous in the case of wells which have been completed in a plurality of producing formations, each of which is connected to a separate string of tubing, the several strings of tubing being enclosed within a surrounding casing which necessarily creates a restricted area, seriously limiting freedom of movement of tubing strings and equipment mounted thereon. Since the usual gas lift mandrels and valves ordinarily form lateral protrusions from The pipe strings, those on one string will interfere with those on another when efforts are made to run one string into the confining casing after another is already in place, and also such protrusions will interfere with rotation inside the surrounding casing of the pipe strings, such rotation being often necessary to complete the installation of the tubing strings in a multiple string well.

Wells have heretofore been equipped initially with tubing strings having gas lift mandrels preinstalled with gas lift valves in place, or with valve dummies which may later be replaced with gas lift valves, in anticipation of the time when the particular producing formation may have to be put on artificial lift. Such systems are subject to numerous difficulties, particularly in protecting the preinstalled valves from the collection thereon of sand or other detritus carried by the well fluids or from corrosion by the latter, so that when the occasion arises to place the valves in operation, they cannot be caused to function effectively and the valves or the tubing string, as a whole, must be pulled in order to correct the condition.

The present invention is directed to a gas lift mandrel which is designed particularly for pre-installation in one or more production tubing strings and which obviates the principal difliculties, such as those mentioned above, to which more conventional systems are subject.

More particularly, the present invention is directed to a form of gas lift mandrel adapted for pre-installation in a production tubing string initially installed in a well, and incorporating within the wall of the mandrel passage means adapted for establishing fluid communication between the interior and exterior of the tubing, and having preinstalled, also within the confines defined by the inner and outer wall surfaces of the mandrel, a gas lift valve in controlling relation to the passage means. The inner end of the passage means will be initially closed by the inner Wall surface of the mandrel to exclude tubing fluids from communication with the valve. The mandrel is also provided with means in the bore thereof operable to effectively locate a wall-perforating device of any suitable form in registry with the inner end of the passage means, so that when required, an opening may be formed through the inner wall surface to communicate the passage means with the interior of the tubing string. Thus, the preinstalled valve is maintained in inactive condition, protected from the well fluids until such time as its operation will be required for effecting artificial lift.

In one embodiment of this invention, the outer end of the passage means is maintained in open communication with the exterior of the mandrel and, therefore, with the interior of the surrounding casing. This arrangement is particularly applicable when the casing surrounding the tubing string does not contain any fluids which might have any deleterious effect upon the valve.

In another embodiment of this invention, the outer end of the passage means will also be closed off, so that the valve will be fully protected from fluids both inside and outside the tubing string. In this embodiment, the closure means for the outer end of the passage means is constructed to be removable by fluid pressure from the interior of the tubing string, once an opening has been created through the inner wall of the mandrel, as previously described. Thus, the passage means will be opened for communicating the interior of the tubing with the exterior thereof under the control of the gas lift valve.

Other and more specific objects and advantages of this invention will become more readily apparent from the following detailed description when read in conjunction with the accompanying drawing which illustrates two useful embodiments in accordance with this invention.

In the drawing:

FIG. 1 is a longitudinal, sectional view of a well having inserted therein a tubing string fitted with a gas lift mandrel in accordance with one embodiment of this invention, the parts being shown in the condition at which the valve-controlled passage means is closed ofi? from communication with the tubing string;

FIG. 2 is a view similar to FIG. 1, showing the passage means in opened communication with the tubing string;

FIG. 3 is a longitudinal, sectional view, generally similar to FIG. 1 illustrating another embodiment in accordance with this invention, the parts being shown in th positions occupied when communication is closed off between the interior and exterior of the tubing string; and

FIG. 4 is a fragmentary view showing details of the structure of FIG. 3 with the parts in positions occupied when communication has been established between the interior and the exterior of the tubing string.

Referring first to the embodiment illustrated in FIGS. 1 and 2, the mandrel comprises a generally tubular body, designated generally by the numeral 10, having threaded connections 11 and 12 at its opposite ends for connecting the body into adjacent sections of a tubing string T, the

latter being shown enclosed within a well casing W. Th wall of body is defined by inner and outer wall surfaces 14 and 15, inner wall surface 14 defining the axial bore 16 of the body, which is substantially flush with the bore of the tubing string. Body 10 may be made up of a plurality of inter-connected sections, as shown, or in any other suitable and known arrangement, to provide the structural details to be described.

Adjacent its upper end the exterior of body 10 is provided with an annular recess 17 which is deepened at one side to form a generally cylindrical pocket 18 adapted to receive a gas lift valve, designated generally by the numeral 19, the depth of the pocket being such that valve 19 will be confined entirely within the body wall between inner and outer wall surfaces 14 and 15. Valve 19 may be of any suitable and generally conventional construction, having ports 20 and 21 arranged in the conventional manner for the passage of pressure fluids through the valve under control of conventional valve mechanism, not shown, but well understood by thse skilled in the art. Recess 17 and pocket 18 are enclosed by a concentric perforate screen 22 arranged to be flush with the outer wall of body 10. At a point spaced longitudinally belOW pocket 18, body 10 is provided with an annular chamber 23 which initially is fully enclosed between the portions 23a and 2312, respectively, of inner and outer wall surfaces 14 and of the body. A passageway 24 likewise confined between the inner and outer wall surfaces of the body, communicates chamber 23 with port 21 of the valve.

It will be seen that portion 23a, which defines the inner wall of chamber 23, serves to initially close off communication between chamber 23 and bore 16 of the body, but when pierced or perforated in a manner to be described, will provide an opening 28 (FIG. 2) to establish such communication.

From the foregoing, it will be seen that chamber 23, when provided with openings 28, passageway 24, and pocket 18 constitute flow passage means providing fluid flow communication between the interior of body 10 and the exterior of the body through pocket 18 under control of valve 19. However, as noted, until openings 28 are provided, valve 19 will be protected from fluids being produced through tubing T and will be exposed only to fluids, if any, which may be present in casing W.

In order to provide openings, when and as required, the mandrel, in accordance with the present embodiment, is provided with means which will enable openings 28 to be formed in the inner wall 2311. This means includes an annular recess 25 in the wall of bore 16 spaced below chamber 23 and defined by upper and lower shoulders 26 and 27, respectively. Recess 25 constitutes a locator seat for a perforating gun G, which may be of any known design, which carries on its lower end a hinge-type latch L, also of known design, which, when disposed in recess 25, will serve to positively position the perforating element, indicated at C, opposite wall portion 234 and in register with chamber 23.

With the arrangement above described, it will be seen that whenever it becomes desirable to activate gas lift valve 19 for controlling admission of lifting gas into the tubing string, perforating gun G will be run through tubing T by using any suitable and generally conventional operating means for this purpose, and moved downwardly until latch L engages in recess 25. Thereafter, gun G may be fired by known procedures to perforate the inner wall portion 23a of chamber 23 and form perforations 28. The gun will then be withdrawn from tubing T and fluid communication will now have been established between the interior and exterior of tubing T under the control of gas lift valve 19, so that conventional gas lift operations may be performed.

Referring now to FIGS. 3 and 4, these illustrate another embodiment in which the gas lift valve is so arranged as to be protected initially from exposure to fluids both inside and outside the tubing string until such time as the valve is to be activated for controlling the injection of lifting gas into the tubing string.

In this embodiment, the mandrel comprises a tubular body, designated generally by the numeral 30, defined by the inner and outer wall surfaces 31 and 32, inner wall surface 31 defining the axial bore 33 extending through the body. The upper and lower ends of the body carry threaded means 34 and 35, respectively, for connecting the body into adjacent sections of tubing string T, the body being shown disposed inside the casing section W. An annular pocket 36 is provided in the wall of body 30 between the inner and outer -wall surfaces and is adapted to receive and fully enclose a gas lift valve 119, as in the previously described embodiment, the valve having ports 37 and 38 for passage of fluid therethrough under control of the usual internal valve mechanism.

A chamber 39 is provided in the wall of body 30 between the inner and outer wall surfaces thereof at a point longitudinally spaced above pocket 36 and communicates with the latter by means of a passage 40 confined between the wall surfaces of the body, under control of gas lift valve 119. The portion 39a of the inner wall of body 30 which defines the inner wall of chamber 39 is initially closed to communication with the bore of the body, as seen in FIG. 3.

A second passage 41 extends longitudinally between the wall surfaces of the body and is arranged to communicate pocket 36 with the exterior of body 30 through a recess 42 which is covered by perforate screen 43. The outer or lower end of passage 41 is counterbored at 44 to receive a sealing plug 45, which is frictionally held against dislodgement from counterbore 44. As best seen in FIG. 4, the inner end of passage 41 is fitted with an inwardly opening check valve, designated generally by the numeral 46, and comprising a cage 47 adapted to be screwed into the upper end of passage 41. Cage 47 is provided with a tubular seat 48 communicating with passage 41, a ball valve 49 adapted to cooperate with seat 48, and outlet ports 50 communicating with the interior of pocket 36. A spacer rod 51 is slidably disposed in passage 41 and has a length such that when its lower end rests on plug 45, its upper end will thrust ball valve 49 away from seat 48 (FIG. 3). When, however, plug 45 has been displaced from counterbore 44, rod 51 will fall through passage 41 allowing ball valve 49 to drop onto seat 48 (FIG. 4) and thus be made operative to perform its normal check valve function of opening to allow inward flow of fluid through passage 41 and closing to prevent fluid flow in the opposite direction.

The bore of body 10 is provided with a locator seat 125, substantially identical in form and function to recess 25 of the previously described embodiment, in order to enable positioning of a perforating gun G in register with chamber 39 when necessary to perforate wall portion 39a.

As will be seen, while wall portion 39a remains imperforate and plug 45 is in place, closing the lower end of passage 41, gas lift valve 119 will be completely encased within the wall of the mandrel body and will not be exposed to fluids, either from the interior or the exterior of body 30, so that when the mandrel containing the gas lift valve is installed in the tubing string, it may be maintained in this protected and inactive condition for as long as may be necessary. When, however, it is desired to activate the gas lift valve, it is only necessary to run a perforating gun G, as in the previously described embodiment, to engage latch L in seat 125, so as to position the perforating element C opposite wall portion 39a and upon firing of the gun, opening 128 will be formed through wall portion 39a, thereby communicating the interior of the tubing string with chamber 39.

When this communication has been established and a head of fluid accumulated in tubing T to an extent sufficient to open gas lift valve 119, the fluid under the pressure thus developed will flow out of ports 37 into pocket 36 and thence through the then open check valve 46 into passage 41 where the pressure will act against plug 45 to force it out of counterbore 44, allowing rod 51 to drop away from ball valve 49 and placing passage 41 into communication with the exterior of the mandrel through recess 42 and screen 43, and activating the check valve to function normally.

The gas lift valve will nOW be free to operate in the normal manner determined by the relationship of the pressures inside and outside of the tubing string in accordance with conventional gas lift systems.

It will be evident that with openings 128 provided through wall portion 39a and plug 45 expelled from passage 41, recess 42, passage 41, pocket 36, passage 40, and chamber 39 will jointly constitute a passageway enclosed entirely within the confines of the wall surfaces of body 30 and communicating the interior of the tubing with the exterior thereof under the control of gas lift valve 119. While the form of the passage thus provided may vary in many details, the important feature is that the mandrel is provided with passage means for communicating the interior and exterior thereof, and in which is mounted a gas lift valve for controlling the passage, the passage being initially closed at both its ends and adapted to be opened for fluid communication between the interior and exterior of the mandrel when openings have been made through the wall of the mandrel into communication with the inner end of the passage.

It will be understood that various Other modifications and alterations may be made in the details of the illustrative embodiments without departing from the spirit of the invention.

What I claim and desire to secure by Letters Patent is:

1. A gas lift valve mandrel, comprising:

(a) a tubular body connectible into a well pipe string to form a part thereof;

(b) longitudinally extending passage means confined between the inner and outer wall surfaces of said body for establishing fluid communication between the interior and the exterior of said body;

(i) the inner end of said passage means being initially closed off by the inner wall surface of said body;

() a gas lift valve mounted within said passage means in flow-controlling relation thereto; and

(d) means in the bore wall of said body operable to locate a wall-perforating device interiorly of said body in registry with said inner end of said passage means when required to form an opening through said inner wall surface to place said passage means in communication with the interior of said body.

2. A gas lift valve mandrel according to claim 1 wherein said means in the bore wall comprises an annular recess defined by longitudinally spaced shoulders.

3. A gas lift valve mandrel according to claim 1 including closure means initially closing the outer end of said passage means, and removable therefrom in response to fluid pressure in said passage means.

4. A gas lift valve mandrel according to claim 3 including inwardly-opening check valve means in said passage means between the outer end thereof and said gas lift valve, and means cooperating with said closure means to inactivate said check valve means when said closure means is in the passage-closing position and to release said check valve means upon removal of said closure means from said passage means.

5. A gas lift valve mandrel for well pipe strings, comprising:

(a) a tubular body connectible into a well pipe string to form a part thereof;

(b) a pocket formed between the inner and outer wall surfaces of said body adapted to receive a gas lift valve;

(c) a chamber longitudinally spaced from said pocket formed entirely between the inner and outer wall surfaces of said body and initially closed to communication with the interior of said body;

(d) a passageway within the wall of said body communicating said pocket with said chamber;

(e) a gas lift valve mounted in said pocket in flowcontrolling relation to said passageway; and

(f) means in the bore wall of the body for locating a wall-perforating device interiorly of said body in registry with said chamber when required to place said chamber in communication with the interior of said body.

6. A gas lift valve mandrel for well pipe strings, comprising:

(a) a tubular body connectible into a well pipe string to form a part thereof;

(b) a pocket formed between the inner and outer wall surfaces of said body adapted to receive a gas lift valve;

(0) a chamber longitudinally spaced from said pocket formed between the inner and outer wall surfaces of said body and initially closed to communication with the interior of said body;

(d) a first passageway within the wall of the body communicating said pocket with said chamber;

(e) a gas lift valve mounted in said pocket in flowcontrolling relation to said first passageway;

(f) a second passageway communicating said pocket "with the exterior of said body;

(g) closure means initially closing off said second passage to the exterior of said body and movable to passageway-opening position by fluid pressure in said pocket in excess of that exteriorly of the body;

(h) inwardly opening check valve means mounted in said second passageway between said pocket and said closure means;

(i) means operable when said closure means is in said closing-off position to hold said check valve means open and to release the same when the closure means is moved to said passageway-opening position; and

(j) means in the bore wall of said body for locating a wall-perforating device interiorly of said body in registry with said chamber when required to place said chamber in communication with the interior of said body.

7. A gas life valve mandrel according to claim 6 wherein said last-mentioned means comprises an annular recess defined by longitudinally spaced shoulders.

References Cited UNITED STATES PATENTS 2,781,098 2/1957 Bielstein 16655.1 XR 3,101,735 8/1963 Brown 137-455 3,175,617 3/1965 North 166-551 XR 3,405,647 10/1968 Bryan 137-155 XR ROBERT G. NILSON, Primary Examiner US. Cl. X.R. 

